I just did the same thing a couple weeks ago. put a heap of matteresses and old tyres (minus rims) on the ground. Then dad, my bro, and myself lifted it onto its side. It had no motor in it at the time, the only thing that leaked was the brakes
the front fender was off on that side, but the doors were still on. No injuries were sustained to the car, except where the brake fluid dripped on the paintwork... but i repainted the engine bay since. (and it was properly on its side, not halfway like this pic)
instead of using those high quality poles, we tied it to a verandah post with a snatch strap.
makes it heaps easier to work on, especially when you have to paint underneath.